The present invention relates to a gas-hydraulic shock absorber assembly, particularly for push and/or pull devices of rail vehicles. It comprises a sleeve member, a ram member movable relative to the sleeve member, a gas chamber located in the sleeve member or in the ram member and adapted to be pressurized by means of a gaseous medium, and an oil chamber located in the ram member or in the sleeve member and containing a hydraulic medium.
Gas-hydraulic shock absorber assemblies to be used in push devices or pull devices of rail vehicles are well known in the prior art, for instance in the form of so-called bumpers. However, a shock absorber assembly designed according to the invention can also be used for example in couplings of rail vehicles, particularly couplings adapted to interconnect a plurality of rail vehicles.
In known gas-hydraulic shock absorber assemblies having no physical separation means to separate the gaseous and fluid media, the fundamental danger is present that gaseous medium collects in the fluid chamber after a certain period of use; of course, this is highly undesirable because it can impair the proper function of the shock absorber assembly, even lead to malfunction thereof. For example, too much gaseous medium in the fluid chamber can lead to an undefined or insufficient resilient behavior e.g. of a rail vehicle bumper. Particularly, if such a bumper is hit very hard, there is a high danger that gaseous medium enters the fluid chamber.
Thus, it is an object of the invention to provide a gas-hydraulic shock absorber assembly of the kind mentioned herein before which bleeds itself during its operation by automatically recycle any gaseous medium that may have collected in the fluid chamber to the gas chamber.
In order to meet this and other objects, the present invention provides a gas-hydraulic shock absorber assembly, particularly for push and/or pull devices of rail vehicles. It comprises a sleeve member, a ram member movable relative to the sleeve member, a gas chamber located in the sleeve member or in the ram member and adapted to be pressurized by means of a gaseous medium, and an oil chamber located in the ram member or in the sleeve member and containing a hydraulic medium.
Further, the shock absorber assembly comprises a gas-hydraulic control assembly arranged between the gas chamber and the oil chamber, and a bleeding assembly, incorporating a transfer channel opening into an upper portion of the oil chamber and providing a communication between the oil chamber and the gas chamber.